JPH0480271B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for diagnosing an abnormality in an injection device of a die-casting machine. Check for abnormalities in the control system of control valves such as stepping motor-driven flow control and pressure control valves that adjust the flow rate or pressure of fluid by moving the spool inside the valve body using a stepping motor that determines the rotation angle. , relates to a method useful for automatic detection and diagnosis on the control device itself.

In die casting machines and injection molding machines, the injection speed has a large effect on the quality of the molded product, leading to malfunctions in the flow control valve that controls the injection speed and its control system, leading to molding defects. At the same time, the filling pressure has a large effect on the quality of the molded product, and if an abnormality occurs in the pressure control valve that controls the filling pressure or its control system, it will lead to molding defects. As labor-saving and automation progress, it is no longer necessary for workers to be near machines at all times, so when an abnormality occurs in the control valve and its control system, if there is no function to detect the abnormality as in the past, If left as is, there is a risk of producing a large number of defective molded products.
As a measure to prevent this, if an abnormality occurs in the control valve that controls flow rate or pressure and its control system, the abnormality is immediately detected, an alarm is issued, production is stopped, or It is desirable to correct the abnormality and return it to a normal state.

In view of the above circumstances, the present invention provides an injection device for a die-casting machine that includes a stepping motor-driven control valve that controls the flow rate and pressure of hydraulic oil, and a control system that includes a stepping motor, a drive unit, and a control device. This provides a self-diagnosis method in which the control device itself automatically detects whether it is normal or abnormal.

[Prior Art] A control valve driven by a stepping motor is generally configured with open loop control, so that the entire device can be simplified.

However, in open loop control, when the machine is first operated, the current position of the spool is recorded in the control device by aligning the spool to the reference position using a detector that detects the reference position or a mechanical stopper. is made to be known, and by outputting the number of command pulses corresponding to the relative distance to the target position based on that position, the robot is moved to the target position. Next, using that target position as the current position, movement to the next target position is performed in the same manner as described above.

[Problems to be Solved by the Invention] As can be seen from the following, the control device operates on the assumption that the spool position of the flow control valve moves in accordance with the number of command pulses. In open-loop control, no detector is provided to provide feedback on the spool position, so the control device does not know whether the spool is actually moving as instructed.

[Means and effects for solving the problem] Therefore, in the present invention, the spool is moved to the detection position of a detector provided to detect the reference position, and the actual spool position is determined from the spool calculated in the control device. By checking whether there is a deviation from the position, it is determined whether the stepping motor-driven control valve and its control system are normal or abnormal.

The time to check the discrepancy between the actual spool position and the spool position calculated in the control device is every time you perform a spool positioning operation.After that, if you perform a spool position confirmation operation, the spool positioning operation will be performed. Depending on the operating state of the machine to be controlled, there are cases where the spool position must be held after the completion of the spool positioning operation until the subsequent spool positioning operation, and there are cases where the spool position must be maintained until the subsequent spool positioning operation. There may be cases where it is okay to move freely.

If the spool position must be maintained for each shot, the spool is moved from the opening position for high-speed injection to the later valve closing direction, i.e. While the spool is moving from the opening position for high-speed injection to the opening position for extruding the cast product when the mold is opened, or
After injection, the molten metal in the mold cavity solidifies to some extent by cooling, and mold clamping continues for a while until it completely solidifies, but after it is no longer necessary to apply pressing force with the injection cylinder, high-speed Is it in the middle of moving from the opening position for injection to the valve closed position, or is it in the middle of moving from the opening position for extruding the cast product to the valve closed position when the spool is at the injection plunger forward limit when the mold is closed? When the spool passes a reference position detected by a reference position detector while the spool is moving from the opening position for injection plunger retreat to the valve closing position at the retraction limit of the injection plunger, a detection signal is generated from the reference position detector. Based on this, the presence or absence of any abnormality in the control valve and its control system shall be confirmed.

If the actual spool position deviates from the calculated spool position, it is diagnosed as an abnormality, and the stepping motor is driven according to the direction and degree of deviation to eliminate this deviation before the next shot. It can be done.

In addition, when the piston of the cylinder for moving the injection plunger is stopped at its travel limit position and no pressure oil is acting on the chamber on the travel end side of the piston, the state of the machine to be controlled is such that the spool is If it is allowed to move freely, use a mechanical stopper to prevent it from being stopped so that foreign objects caught between the valve fluid passage and the spool, as well as abnormalities in the power transmission mechanism or sliding parts, can be detected. After moving the bent spool within the movable range and finally returning to the reference position, check for abnormalities in the control valve and its control system based on the detection signal from the reference position detector. I'll do what I do.

If the actual spool position deviates from the calculated spool position, it is diagnosed as an abnormality, and the stepping motor is driven according to the direction and degree of deviation to eliminate this deviation before the next shot. can do.

[Example] Next, the present invention will be explained with reference to an example shown in the drawings.

Figure 1a shows a diagram of the flow control valve control system in a die casting machine, and Figure 1b
1 shows a schematic diagram of an injection plunger speed control pattern.

In Fig. 1a, 1 is an injection cylinder, 2 is an injection plunger, 3 is an injection sleeve, 4 is a fixed mold, 5 is a movable mold, 6 is a fixed plate, 7 is a movable plate, and 8
is a striker attached to the injection plunger 2, 9 is a limit switch that operates at the retraction limit of the injection plunger 2, 10 is a limit switch that outputs a switching signal from medium-speed injection to low-speed injection, and 11 is a switching signal from low-speed injection to medium-high speed injection. A limit switch 12 outputs a switching signal from medium to high speed injection to high speed injection. Note that these limit switches 9 to 12 may be replaced with other position detectors such as magnetic scales. 13 is a valve opening setting device, 14 is a die casting machine controller (sequencer), 15 is a stepping motor controller, 16 is a drive unit, 17
1 is a stepping motor also called a pulse motor, 18 is a flow control valve, 19 is a hydraulic pressure source, and 20 is a reference position detector for the stepping motor 17, which are linked together as shown in FIG. 1a.

The injection plunger speed control system is set in advance by commands from a valve opening setting device 13, a die-casting machine controller (sequencer) 14, and signals from limit switches 9 to 12 set at predetermined positions during the stroke of the injection plunger 2. The rotation angle of the stepping motor 17 is controlled by the valve opening degree of the flow rate control valve 18. Note that in this system, the valve opening degree can be set to any desired opening degree, and the valve opening speed can also be changed.

The valve opening degree and the accompanying injection speed during injection are controlled, for example, as shown in FIG. 1b. In FIG. 1b, 9a to 12a shown on the horizontal axis indicating the injection stroke are positions corresponding to the operating positions of limit switches 9 to 12, respectively, where A is medium speed, B is low speed, C is medium high speed, and D is medium speed.
indicates high speed.

The valve opening degree setting device 13 shown in FIG. 1a sets the value of the valve opening degree for each stroke 9a to 12a during injection.

The die-casting machine controller 14 controls the entire die-casting machine using a sequencer. Then, in accordance with the operation of the die casting machine, control data such as an injection start command and an injection retreat command are output to the stepping motor controller 15, and at the same time, the opening setting value is read from the valve opening setting device 13, and this controller 15 and performs an answer backup check on the same data.

The drive unit 16 has a DC power supply and a phase excitation switching function, and drives the stepping motor 17 using rotation direction data and pulse signals from the controller 15.

In the flow control valve 18, a stepping motor 17 is connected to a valve control operation shaft connected to the spool,
Stepping motor and shaft rotation angle and shaft rotation speed
Changed by a control signal from the controller 15,
Controls the supply flow rate to the injection cylinder 1. Before starting injection, the flow control valve 18 is fully closed, and the sequencer 1
In response to the injection start command from step 4, the valve opening degree and opening speed are sequentially changed according to, for example, an exponential function program in the stepping motor controller 15.

The reference position detector 20 detects the movement reference position of the valve operating shaft 26 connected to the spool 24 of the flow rate control valve 18 illustrated in FIG.

The flow rate control valve 18 has a structure as shown in FIG. 2, for example. In FIG. 2, 21 is a valve body having a hydraulic oil inlet 22 and a hydraulic oil outlet 23, 24 is a spool that moves in the axial direction in the valve body 21, and 25 is attached to a valve operating shaft 26 which is the rear shaft of the spool 24. ball screw, 27
1 is a pinion gear device, 17 is a stepping motor, 20 is a reference position detector for detecting the reference position, 28 is a magnetic body attached to the reference position, and the reference position detector 20 detects when this magnetic body 28 approaches. and outputs a detection signal. In addition, in this flow rate control valve 18, when the valve is closed and the flow rate is 0, the tip of the spool 24 is in a position where it can slide left and right without contacting the back wall of the valve body 21. ing.

In open-loop control using the stepping motor 17, the reference position has conventionally been confirmed by the reference position detector 20 when the power is turned on, but in this embodiment, the piston of the injection cylinder 1 for moving the injection plunger 2 is stopped at its travel limit position, no pressure oil is acting on the chamber on the travel end side of the piston, and there is no mechanical stopper inside the control valve, so the fluid is When the spool 24, which adjusts the flow of the spool 24, is moved so as not to affect the machine operation, the spool 24 is then moved over the entire range within which the spool can be moved, and returns to the reference position again. After outputting the command pulse to the stepping motor 17 as shown in FIG.
A magnetic body 28 attached to the reference position of the part that moves together with the spool 24 is attached to the valve body 2 of the control valve.
When the reference position detector 20 for detecting the reference position attached to the fixed part integral with 1 is moved back to the position, the actual spool position deviates from the calculated spool position in the injection control device. This is confirmed based on the detection signal from the reference position detector 20 for detecting the reference position, and thereby the control including the stepping motor-driven flow control valve 18, the stepping motor 17, the drive unit 16, and the control device Self-diagnosis to see if the system is normal.

In other words, when determining whether or not the actual spool position deviates from the calculated spool position, and if so, how far it deviates in either the valve opening direction or the valve closing direction, this spool As a positional deviation diagnostic device, the magnetic body 28 attached to the spool 24 side and the reference position detector 20 attached to the valve body 21 side are used. When heading to the valve, the stroke or time required for the magnet to move from a predetermined high-speed injection position through the reference position to the fully closed valve position is calculated in advance, and the spool 24 and magnet When 28 moves from the high-speed injection position toward the valve closing direction by the stroke or time determined by the calculation, the direction of the deviation is determined by the sign and magnitude of the voltage transmitted from the reference position detector 20. and detect the degree of deviation. At this time, if the voltage transmitted by the reference position detector 20 is 0, it is determined that there is no deviation at all and that the position is normal.

This means that when the piston of the injection cylinder 1 is at the forward limit or backward limit position, when the spool 24 and the magnetic generator 28 move from the predetermined valve open position to the complete valve close position through the reference position. You can also do the same thing. Similarly, the stroke or time of the magnetic generator 28 is calculated in advance, and the magnetic generator 28 is moved during the valve closing operation.
Normality or abnormality is determined based on the output sent from the reference position detector 20 when the reference position detector 8 actually moves by the value calculated in advance.

If the output from the reference position detector 20 is 0 and is diagnosed as normal, there will be no problem, and it is natural that the subsequent operations and the next shot may be continued as they are.

In the unlikely event that the output from the reference position detector 20 is 0.
If not, it is diagnosed as abnormal. Then, when the piston of the injection cylinder 1 is at the forward limit or the backward limit, the stepping motor 17 is rotated to restore the normal state. In this case, the relationship between the deviation between the magnetizing body 28 and the reference position detector 20 and the output from the reference position detector 20 is determined in advance, and based on this, the positive and negative values of the voltage output from the reference position detector 20 are determined. , commands the rotation direction of the stepping motor 17, commands the rotation angle of the stepping motor 17 according to the magnitude of the voltage by a pulse signal, rotates the stepping motor 17, and corrects it to a normal state. do.

Therefore, in the unlikely event that the reference position has shifted, the abnormality can be detected before starting the die-casting machine and performing the next injection operation without molding defective products, and the next injection operation can be corrected. It is also possible to correct the spool position and return it to a normal state before performing the operation.

Further, while the die casting machine is in continuous operation, the spool 24 of the stepping motor driven flow control valve 18 moves as shown in FIG. 3 in order to control the movement of the injection cylinder.

The movement of the spool 24 shown in FIG. 3 will be explained below.

When the preparation work such as mold clamping, spraying, and hot water supply for pouring molten metal into the mold is completed and a command to start injection is issued, the spool is moved to the spool position A by the spool positioning operation, and the injection plunger 2 of the injection cylinder 1 is moved to the spool position A. Move from 9a to 10a at medium speed. According to the change in the stroke of injection cylinder 1, the spool positioning operation is performed in the same way in order.
is performed, and the spool 24 is moved to spool positions B, C,
D, and the injection plunger 2 moves at low, medium-high, and high injection speeds. Mold 4,
When the molten metal is filled into the mold 5, the mold opening operation of the mold clamping device is performed after the cooling time of the molten metal has elapsed. In order to move the injection plunger 2 at the injection speed in synchronization with the mold opening speed of this mold opening operation, the spool 24 is moved to the spool position E by the positioning operation. In this case, the spool position was moved directly from D to E, but this is because the molten metal in the mold cavity solidifies to some extent by cooling after injection, and mold clamping continues for a while until it completely solidifies. However, after it is no longer necessary to apply pressing force with the injection cylinder, in order to minimize energy loss, the valve is moved from the D position to the valve closed position as shown by the dotted line in Figure 3. Thereafter, the spool can be moved to the E position by a spool positioning operation' at the start of mold opening.

When the injection plunger 2 reaches its forward limit, the spool 24 is moved to a fully closed spool position by a spool positioning operation.

In order to retract the injection plunger 2 to the retraction limit for the next casting, the spool 24 is moved to the spool position F by the spool positioning operation. When the injection plunger 2 retreats to the retreat limit 9a, the spool 24 is moved by the spool positioning operation.
is moved to the fully closed spool position. Mold 4, 5
When the die-casting product is taken out,
The initial casting preparation operation is performed again, and the above operations are repeated cyclically during continuous operation.

In this case, when detecting the reference position during the spool positioning operation, E
It is preferable to provide the reference position at a position relatively close to the position. Alternatively, if the reference position is set closer to the valve closed position than the E and F positions,
It is possible to detect whether or not the reference position is reached during any of the spool positioning operations. Note that, for example, it will be more reliable if both are detected.

FIG. 4 shows a flowchart of the operation operation in which a self-diagnosis function of the stepping motor-driven flow rate control valve control system is added in consideration of the operating state of the die-casting machine described above.

In FIG. 4, the area surrounded by a double frame is where self-diagnosis according to the present invention is being performed, and the other areas are where normal injection operation is being performed.

Note that at the forward limit and backward limit of the injection cylinder, the hydraulic pump may be unloaded, or the hydraulic pump may remain driven.

The self-diagnosis of the stepping motor-driven flow control valve control system when the power is turned on is as described above.

During continuous operation of the die casting machine, the spool 24 of the flow control valve 18 is moved according to the set injection speed pattern in order to control the speed of the injection cylinder during the injection process of injecting molten metal into the mold. The 18 spools 24 cannot be moved freely.

In addition, during the injection progress and until high-speed injection is performed, the injection speeds of medium, low, medium-high, and high speeds are often changed and adjusted as appropriate depending on the product to be injected, so it is necessary to keep them within this operating range. It is not a good idea to determine the reference position and diagnose the presence or absence of an abnormality because the reference position detection becomes unstable due to the influence of speed setting changes. On the other hand, the spool position at the final stage speed (high speed) D of the injection process is large, and the spool position E at the extrusion speed is small, and the injection cylinder speed ratio is about 5:1 to 10:1, so the spool 24 is moved from spool position D to E. Since the reference position detector 20 can be installed to detect the reference position near the E position during the injection process, it is possible to detect abnormalities in the stepping motor-driven flow control valve control system during the injection process. Self-diagnosis is performed when passing a reference position near position E during positioning operation from spool position D at high speed to spool position E at extrusion speed.

In addition, while the spool 24 is moving from the opening position for high-speed injection toward the later valve closing direction, the magnetizing body 28 attached to the reference position of the part that moves together with the spool 24, When passing the position of the reference position detector 20 for detecting the reference position attached to the fixed part integral with the valve body 21 of the control valve 18, the actual spool 24 position deviates from the calculated spool 24 position in the injection control device. In this way, it is confirmed based on the detection signal from the reference position detector 20 whether the spool 24 is moving from the opening position for high-speed injection to the opening position for extruding the cast product when the mold is opened. In addition to being in the middle of movement, the spool 24 may be in the middle of moving from the open position for extruding the cast product when the mold is opened to the fully closed position of the valve at the forward limit of the injection plunger 2, or the spool 24 may be in the middle of the injection. It may be performed while the plunger 2 is moving from the retracting opening position to the fully closed position of the valve at the retracting limit of the injection plunger 2.

Also, after injection, the molten metal in the mold cavity solidifies to some extent by cooling, and mold clamping continues for a while until it completely solidifies, but after it is no longer necessary to apply pressing force with the injection cylinder, ,
If the energy loss is to be reduced by moving from the open position for high-speed injection to the valve closed position, the movement can also be carried out near the valve closed position during the movement.

Furthermore, the forward movement limit of the injection plunger 2, which is the extrusion limit of the cast product during the mold opening operation, and the injection plunger 2
At the retraction limit, when the piston of the injection cylinder 1 for moving the injection plunger 2 is stopped at the movement limit position and no pressure oil is acting on the chamber on the movement limit side of the piston, the flow rate is Even if the spool 24 of the control valve 18 is freely moved, the injection plunger 2 of the injection cylinder 1 does not operate, and the movement of the spool 24 does not affect the machine operation.
After outputting a command pulse to the stepping motor 17 to move the spool 24 over the entire movable range of the spool 24 and finally return to the reference position, a reference position detection signal from the reference position detector 20 is output. By checking this, it is possible to self-diagnose whether or not there is an abnormality in the stepping motor-driven flow control valve control system.

When an abnormality is detected by the self-diagnosis of the stepping motor-driven flow control valve control system, if the degree of deviation of the actual spool position from the calculated spool position is relatively small, the stepping motor Drive the spool to move the spool to eliminate this deviation before the next shot, and continue operation. Of course, if this deviation is relatively large,
Since the degree of abnormality is large, it would be dangerous to continue operation as it is, and the die casting product cast in that condition would be judged to be defective. By stopping the machine in an appropriate state, issuing an alarm, and correcting the defective parts, it is possible to prevent a large number of defective molded products from being produced.

In the above embodiment, one reference position was set at a fixed position, but this
It is not necessarily limited to this, but it is possible to provide a plurality of reference points or change the position, for example, when the spool is in the valve open position for high-speed injection, it moves toward the later valve closing direction. It is also possible to provide a reference position so that the injection plunger 2 acts while the injection plunger 2 is moving, and also to provide a reference position that acts when the injection plunger 2 is at its retracting limit position.

Furthermore, the reference position detector may be activated when the control valve spool is moving from a wide open state to a closed direction and moving to a predetermined opening position, or when the control valve spool is moving toward a predetermined opening position. From a wide open state, it suddenly closes and then opens immediately.
It may also be when moving to a predetermined opening position. Further, the reference position can also be set to the fully closed position of the spool.

Further, although the above embodiments have been described using a flow control valve as an example, the present invention can be similarly applied to a stepping motor-driven pressure control valve of a die-casting machine.

[Effects of the Invention] As described above, in the present invention, by using the reference position detector, the stepping motor-driven control valve, the stepping motor, and the drive unit can be easily installed without adding any special parts or equipment. , it is now possible to self-diagnose abnormalities in the control system consisting of the stepping motor controller, and it is possible to quickly deal with abnormalities before they generate a large number of defective molded products, making it possible to prevent the occurrence of a large number of defective molded products. Productivity can be improved.

In the present invention, since the injection device of the die-casting machine is self-diagnosed to determine whether there is an abnormality, if there is an abnormality in the detection of the reference position, it is determined that the die-cast product is defective.
By correcting the abnormal condition, it is possible to obtain a cast product of good quality.

In particular, in the present invention, in the injection device of a die-casting machine, the spool that is slidably provided in the control valve and adjusts the flow of fluid moves from the opening position for high-speed injection toward the rear valve closing direction. Since the reference position is detected during movement, changing the injection speed will have no effect on die casting machines, where the injection speed setting value is often changed depending on the shape and dimensions of the cast product. The reference position can be detected even when there is no reference position. That is, the difference between the high-speed injection speed and the forward speed of the injection plunger and the backward speed of the injection plunger when extruding the product when the mold is opened is usually very large; The retraction speed of the injection plunger is not affected by changes in the high-speed injection speed, and is almost never changed for any cast product, so the reference position is set at a location that will not be affected by changes in the set value of the injection speed. There is no problem even if this reference position is fixed, and the reference position can always be detected reliably. Also, since the reference position is detected while the spool is moving in the valve closing direction,
Unlike when it is necessary to move the spool in an extremely short period of time under high load, such as when transitioning to high-speed injection, the reference position is set when the spool is moving relatively slowly with almost no load applied. can be detected with good detection accuracy and can be detected easily and reliably.

In addition, the forward speed of the injection plunger and the backward speed of the injection plunger when extruding the product when the mold is opened are relatively low speeds, for example, about 1/5 to 10 times smaller than the high speed injection speed, so the reference position A detector having a measurement function suitable for the frequency corresponding to this relatively low speed can be used. In addition, since the load is light at this time, accurate detection can be achieved.

Of course, if the actual spool position deviates from the calculated spool position because the pulse counting device is broken, the pulse count is incorrect due to noise, or the pulse drive part goes out of step, Since the stepping motor can be driven for each shot to eliminate deviations before the next shot or immediately, errors can be easily and easily eliminated for each shot, and errors will not be accumulated. , it is possible to reliably secure the zero point position when the valve is closed for each shot, and to obtain a good injection condition every time.

In addition, if you install two reference position detectors instead of just one, you can naturally check the position at two locations for each shot.
The degree of certainty can be further increased, and the degree of reliability is further improved.

In addition, in the present invention, the piston of the cylinder for moving the injection plunger is stopped at its movement limit position, and no pressure oil is acting on the chamber on the movement limit side of the piston, so that there is no pressure inside the control valve. If there is no mechanical stopper and the spool is slidable and adjusts the flow of fluid, moving the spool will not affect the mechanical operation, then move the spool within the movable range to determine the standard. Since the position can also be detected, when the spool is at the reference position and stopped at the valve closed position, the end face of the spool can be moved from side to side without having to be stopped by a mechanical stopper such as making it come into contact with the back wall. Coupled with this wet condition, the spool can be reliably and easily moved to a position where the magnetizing body always coincides with the reference position. That is, when a mechanical stopper is used, in some cases, the magnetizing body stops before the reference position and does not move forward any further, making it impossible to detect the reference position. ,
This does not occur and the spool can be advanced until the magnetizing element always matches the reference position, so the zero reference position can always be detected easily and reliably in any case, and the injection device of the die-casting machine The presence or absence of an abnormality can be fully diagnosed. In this case, the degree of the abnormality can be determined based on the degree to which the magnetizing body is separated from the zero reference position.

[Brief explanation of the drawing]

The drawings are for explaining one embodiment of the present invention, and FIG. 1a shows a flow rate control valve control system in a die-casting machine, FIG. 1b shows a schematic diagram of an injection plunger speed control pattern, and FIG. 2 shows a flow rate control valve control system in a die-casting machine. FIG. 3 is a schematic longitudinal sectional view of the control valve, FIG. 3 is a diagram showing changes in the spool position of the flow control valve used in a die-casting machine, and FIG. 4 is a flowchart of the operation. 1... Injection cylinder, 2... Injection plunger,
3... Injection sleeve, 9-12... Limit switch, 13... Valve opening setting device, 13... Die casting machine controller (sequencer), 1
5... Stepping motor controller, 17...
... Stepping motor, 18 ... Flow control valve, 2
0... Reference position detector, 24... Spool, 25
... Ball screw, 28 ... Magnetizing body.

Claims (1)

[Scope of Claims] 1. A control valve driven by a stepping motor is provided in the injection hydraulic circuit of a die casting machine, and an arbitrary control signal is sent to the stepping motor for driving the control valve when the injection plunger is operated. When operating the injection device of a die-casting machine equipped with this device, the spool is slidably provided for each shot so that the end face of the spool does not come into contact with the wall inside the control valve even when the valve is closed, and the fluid flow is controlled. When the spool that adjusts the control valve is in the opening position for high-speed injection and is moving toward the later valve closing direction, the magnetic generating body attached to the reference position of the part that moves together with the spool opens the control valve. When passing the reference position detector for detecting the reference position attached to a fixed part integral with the valve body, check whether the actual spool position deviates from the calculated spool position in the injection control device. A die casting machine that checks based on a detection signal from a detector, thereby diagnosing the presence or absence of an abnormality in a control valve and its control system, and diagnoses an abnormality if the spool position is deviated. A method for diagnosing abnormalities in injection equipment. 2. A die-casting machine equipped with a stepping motor-driven control valve in the injection hydraulic circuit of the die-casting machine, and a control device that sends an arbitrary control signal to the stepping motor for driving the control valve when the injection plunger is operated. When operating the injection device, for each shot, a spool is slidably provided to adjust the flow of fluid so that the spool and end face do not come into contact with the wall inside the control valve even when the valve is closed. While the valve is moving from the opening position for high-speed injection to the later valve closing direction, the magnetizing body attached to the reference position of the part that moves together with the spool moves to the valve body of the control valve. When passing the position of the reference position detector for detecting the reference position attached to the fixed part, check whether the actual spool position deviates from the calculated spool position in the injection control device using the information from the reference position detector. The control valve and its control system are checked based on the detection signal, thereby diagnosing the presence or absence of an abnormality in the control valve and its control system.If the spool position is shifted, it is diagnosed as an abnormality. , the piston of the cylinder for moving the injection plunger is stopped at its travel limit position, no pressure oil is acting on the chamber on the piston's travel limit side, and there is no mechanical stopper in the control valve. If the spool is slidable and adjusts the flow of fluid, and moving the spool does not affect the mechanical operation, move the spool within its movable range and move it together with the spool. The magnetizing body attached to the reference position of the part,
When the control valve is moved back to the position of the reference position detector for detecting the reference position attached to the fixed part integrated with the valve body, the actual spool position may deviate from the calculated spool position in the injection control device. Based on the detection signal from the reference position detector for detecting the reference position, the presence or absence of an abnormality in the control valve and its control system can be diagnosed. A method for diagnosing an abnormality in an injection device of a die-casting machine, in which a misalignment is diagnosed as an abnormality.